Low exposure of people to microplastics through drinking water

According to a preliminary study, Finnish household water contains only small amounts of microplastics. Water treatment processes effectively remove particles from the raw water that is used in the production of household water, according to a study by the Finnish Environment Institute, the National Institute for Health and Welfare and the Finnish Water Utilities Association.

The study examined raw water used in the production of household water, treated household water that is supplied to the water distribution system, and water distributed from three different types of water treatment installations and their distribution areas. The water utilities that were studied included the Nurmijärvi Water ground water plant at Telinummi, the Jäniksenlinna artificial ground water plant of the Tuusula region water utility (joint municipal authority), and the Vanhakaupunki water treatment plant of the Helsinki Region Environmental Services Authority (joint municipal authority). The two latter installations treat surface water piped in from Lake Päijänne.

“Included in the study were the different types of raw water used in Finland and the most common water treatment processes. In addition, the study analysed bottled water from two different producers for microplastic content. The aim of the study was to develop a method for studying microplastics in household water and at the same time to create the first survey of the microplastic content of Finnish drinking water”, says SYKE researcher Julia Talvitie.

The tap waters and bottled waters that were studied were found to contain a few, 0 - 9 particles of plastic per litre with a size of more than 10 micrometres. Microplastics are particles of plastic under five millimetres in size. As the research involved a preliminary study with a very limited number of samples taken, it is not possible to draw more extensive conclusions on the microplastics content in tap water.

All of the water treatment plants that were studied have a proper treatment process in place with respect to the quality of raw water, which was seen to efficiently remove solid materials, including microplastics, from the raw water.

Research methods for microplastics need to be standardised

“Microplastics in drinking water have been studied in a few countries, including Germany and the Czech Republic. The microplastics content that has been reported varies greatly from one study to another, and it appears that the selected research methods have affected the differences in content. The results suggest that the smaller the microplastics that could be analysed, the higher the set content has been”, notes group director Markus Sillanpää of SYKE, who headed the project.

This Finnish preliminary study investigated the numbers of microplastic particles more than 10 micrometres in size, whereas some studies have reported the amounts of particles with sizes of more than 1 or more than 100 micrometres. It was established in the study that it is essential to develop, harmonise, and standardise the methods of taking samples and analysing microplastics. This would make it possible to compare results from different studies both in Finland and internationally.

“People can be exposed to microplastics through the food they eat and the air they breathe, but so far, the significance of exposure routes for the overall exposure to microplastics remains unknown. Based on this study and other available information, it is possible to estimate that exposure to microplastics through tap water is low in Finland compared with other sources of exposure”, notes Hannu Kiviranta, research professor at THL.